The main differences between public and private cloud computing lie in access and control. Public clouds are owned and operated by third-party providers, allowing multiple organizations to share resources, leading to cost-effectiveness and scalability. They offer flexibility but may raise concerns about security and data privacy. Conversely, private clouds are dedicated to a single organization, providing greater control over security, compliance, and customization. They are ideal for businesses with specific requirements or sensitive data, ensuring that resources are not shared with others and enhancing data protection.